Drying cabinet or incubator for drying surface of agar plates.Same basic equipment as for conventional plate count (Chapter 3).This method is suitable for the analysis of foods in which more than 100 S. This research indicates that none of these tests can be relied upon to differentiate toxic and nontoxic staphylococci. In all cases, the reactions of enterotoxigenic and nonenterotoxigenic strains varied by 12% or less. Studies of colonial morphology on Baird-Parker agar, lysostaphin sensitivity, coagulase and thermonuclease production, and glucose and mannitol fermentation were conducted on 100 enterotoxigenic and 51 nonenterotoxigenic strains of S. aureus on the basis of coagulase reactions of less than 4+ should be confirmed by other tests, such as anaerobic glucose fermentation, lysostaphin sensitivity, and thermonuclease production. A consensus of peers has established that a 4+ coagulase reaction is necessary for unquestioned identification of S. Research results have indicated that the weak coagulase activity represented by 1+, 2+, and 3+ reactions seldom corresponds with other criteria associated with S. There has been considerable controversy about the significance and correct method of reading the coagulase test. aureus that have been studied collaboratively and found suitable for use in providing the type of information necessary for FDA requirements are presented in this chapter. aureus may lead to legal action against the party or parties responsible for a contaminated food. Processed foods may contain relatively small numbers of debilitated viable cells, whose presence must be demonstrated by appropriate means. aureus depend on the reasons for testing the food and on the past history of the test material. Therefore, the analyst should consider all possibilities when analyzing a food for S. Conversely, small staphylococcal populations at the time of testing may be remnants of large populations that produced enterotoxins in sufficient quantity to cause food poisoning. aureus must be shown to produce enterotoxins. aureus organisms in a food may indicate poor handling or sanitation however, it is not sufficient evidence to incriminate a food as the cause of food poisoning. aureus in foods should be made with circumspection. Conclusions regarding the significance of S. aureus is the causative agent of foodborne illness, to determine whether a food is a potential source of "staph" food poisoning, and to demonstrate post-processing contamination, which is generally due to human contact or contaminated food-contact surfaces. aureus and/or its enterotoxins to confirm that S. Foods are examined for the presence of S. It has been identified as the causative agent in many food poisoning outbreaks and is probably responsible for even more cases in individuals and family groups than the records show. Thus, the presence of this bacterium or its enterotoxins in processed foods or on food processing equipment is generally an indication of poor sanitation. Staphylococcus aureus is highly vulnerable to destruction by heat treatment and nearly all sanitizing agents.
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